Study On The Construction Of Au@TiO₂ Heterostructure And Their Plasmon-enhanced Photocatalytic Reduction Of CO₂

Photocatalytic technology as an effective way to solve the environment pollution and energy shortage,which has been attracting the attention of the researchers.However,solar energy utilization is low and quantum conversion efficiency is low,which restrict the development of the photocatalytic technology.The photocatalytic technology combined with plasmon resonance principle to construct the plasmon resonance of the nanomaterials,offers a new way for us to solve the above problems.In this paper with different morphology of gold(rod,pyramid,plate)for the"nuclear",semiconductor titanium dioxide as the”shell",we built the plasmon resonance core-shell nanomaterials.And with Au nanorod@TiO2core-shell materials as representative,combined with the related physical and chemical characterization,explores the different thickness of titanium dioxide in performance of photocatalytic reduction of CO2 and mechanism.This work mainly includes two parts:(1)The construction of core-shell heterostructure by sodium polyacrylic acid(PAA)as modifier,and titanium trichloride(TiCl3)as titanium source,using wet chemical method and electrostatic effect,made the titanium dioxide wrapped in gold nanorod,so as to construct a core-shell heterostructure plasmon resonance materials.Modified process was characterized by Zeta potential and UV-VIS;Three main factors affecting the parcel(solution PH,the molecular weight of PAA,reaction time)were discussed in this paper,in order to optimize the experimental conditions.(2)The study of photocatalytic reduction of CO2 Namely,taking the optimization of experimental conditions in the last chapter,based on the different thickness of core-shell nanomaterials was synthesized(3 nm,10 nm,20 nm,50 nm,110 nm)combined with TEM,EDX,XPS and UV-VIS,and a series of characterization methods and the electron transfer process dynamics research,explored the performance of photocatalytic reduction of CO2 and the mechanism.Paper for the following main innovation results and conclusions:(1)Compared with traditional gold nanorods synthesis method,we found that changing the dosage of the weak reductant AA A(1.55ml-1.30ml),also can make gold nanorods solution of longitudinal absorption peak change(630 nm-850 nm).On this basis,we put forward and proved in the process of formation of the gold nanorods,consumption of Au + is a competing process,in which the seeds grow a gold bar in the shape of a need and good gold continues to grow at both ends.The above findings and conclusions to clarify the growth mechanism of gold nanorods have important reference value.)(2)By developing the new method to synthesis titanium dioxide package gold core-shell nanomaterials and changing the synthesis condition,can realize accurate control for the thickness of the shell(3nm-110nm).At the same time,we parceled other morphology of the gold(triangle flake,cone)by this method,showing that this method also has general applicability.(3)Due to the synthesis of the core-shell structure with uniform dispersion and high yield,it is the first time realized the photocatalytic reduction of C02,and through the different package thickness,electron transfer process was discussed from the Angle of space.At the same time,by femtosecond transient absorption spectra,we confirmed that hot electrons produced by plasmon gold can be injected into the valence band of TiO2 semiconductor and motivate valence band electron transit to the conduction band,to achieve electron-hole separation in TiO2.